Tandem printer



Aug. 9, 1966 J. E. BURGER ET AL 3,264,981

TANDEM PRINTER Filed April 15, 1964 5 Sheets-Sheet l I,. E I 73 i 4/ 35 34 d f gTZ MACHINE MACHINE REVOLUTION P ATIO H IH l5 0 IMAGING TH REE BLANKET THREE PRINT PRE IONS BLANKET INK OF AND REPELLENT BLANKET MACHINE DRIVE Aug. 9, 1966 J. E. BURGER ET AL TANDEM PRINTER Filed A ril 15, 1964 5 Shee ts-Sheet 2 INVENTORS. JA CK E. BURGER FRANCIS M. POLL) BY 2 A TTORNEY Aug. 9, 1966 J. E. BURGER ETAL 3,264,981

TANDEM PR INTER Filed April 15, 1964 5 Sheets-Sheet 5 INVENTORS. JACK E. BURGER FRANc/s N. POLL) WU i867 TANDEM PR INTER 5 Sheets-Sheet 4 Filed April 15, 1964 mwv Q? Aug. 9, 1966 J, URGER ET AL TANDEM PRINTER 5 Sheets-Sheet 5 Filed April 15, 1964 United States Patent 3,264,981 TANDEM PRINTER Jack E. Burger, Chagrin Falls, and Francis M. Polly,

Euclid, Ohio, assignors to Addressograph-Multigraph Corporation, Cleveland, Ohio, a corporation of Delaware Filed Apr. 15, 1964, Ser. No. 352934 Claims. (Cl. 101144) This invention relates to a new and improved printing machine and more particularly to an offset printing machine of the kind comprising first and second printing heads connected in tandem and driven' in unison to perform two sequential printing operations on each of a plurality of print-receiving sheets. The printing machine of the invention includes provision for controlling virtually all machine operations by automatic sequence control apparatus incorporated in the machine, with little or no attention from the machine operator once printing has been initiated.

In Patent No. 3,056,346 to Gammeter et al., issued October 2, 1962, there is disclosed an offset printing machine particularly suitable for applications requiring frequent changes of the material being printed. Machines of this kind are often applied to relatively short printing runs, sometimes referred to as systems printing applications. In the offset printing machine disclosed in the aforesaid Patent No. 3,056,346, the principal control is exercised by a main control member that is movable between an initial position, two intermediate operating positions, and a final printing position. This control member, usually constituting a rotatable shaft, controls the application of ink-repellent solution to a planographic master mounted upon the master cylinder of the machine and also controls the application of ink to that master. In addition, the control shaft, by its movement between its different operating positions, controls the displacement of one of the master and blanket cylinders of the machine from an initial position displaced from the other cylinder into blanketimaging contact therewith, thereby controlling imaging of the blanket. The same control shaft also is used to control a blanket cleaner for cleaning ink from the blanket cylinder of the machine in preparation for a new printing operation.

In some systems applications, it is essential to provide for printing both sides of a sheet in order to condense the total volume of paper required for a given amount of printed data. It is frequently desirable to use the printing machine to prepare a printed form andat the same time to imprint specific data in the form outline. Moreover, it is frequently desirable to print the same sheet in more than one color. In each of these instances, it is necessary to afford more than one printing head in order to achieve the requisite versatility and capacity in the printing machine. In an automatically controlled tandem printing machine, however, it is not desirable to maintain the two printing heads of the machine in complete synchronism with each other, insofar as the sequence of operational steps is concerned, particularly because this may lead to over-inking of the blanket in the second printing head of the machine.

:It is a primary object of the invention, therefore, to provide a new and improved control apparatus for the operation of a tandem offset printing machine, with all operations subsequent to etching of the master completely and automatically controlled in sequence.

More specifically, it is an object of the invention to provide a new and improved timing or programming control means for a dual tandem offset printing machine that is effective to equalize the ink transferred to the blankets in the two printing heads and maintain uniform printing in both heads of the machine.

Patented August 9, 1966 A specific object of the invention is to afford a new and improved automatic sequence control apparatus for a dual tandem offset printing machine that maintains the two printing heads of the machine operating in unison through the initial stages of an automatic control sequence but that defers blanket imaging in the second head of the machine by a time interval equal to the time required for a sheet imprinted in the {first head of the machine to reach the second printing head. A related object of the invention is to afford a timing mechanism for the dual tandem offset printing machine that is inherently actuated in synchronism with machine operations and that cannot get out of step with the machine as long as printing operations go forward in the normal manner.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be made as desired by those skilled in the art without departing from the present invention.

In the drawings:

FIG. 1 is a perspective view of a dual offset printing machine constructed in accordance with a preferred embodiment of the invention;

FIG. 2 is a timing chart utilized to explain the sequence of automatic operations performed by the printing machine of FIG. 1;

FIG. 3 is an elevation View of a major portion of the automatic control apparatus for one printing head of the printing machine of FIG. 1;

FIG. 4 is a detailed drawing of switching apparatus incorporated in the automatic control apparatus of FIG. 3;

FIG. 5 is a detail elevation view of a program control device incorporated in one printing head of the printing machine of FIG. 1, drawn to a larger scale than FIGS. 3 and 4;

FIG. 6 is a detail sectional view taken approximately along line 66 in FIG. 5 and showing a cam-actuated control switch incorporated in the program control apparatus;

FIGS. 6A and 6B are detail views of other cam devices used in the program control apparatus;

FIGS. 8 and 9 together afford a detail schematic dia- I gram of the electrical control circuit for the printing machine.

GENERAL DESCRIPTION A general understanding of the construction and operation of the printing machine of the invention may best be obtained by reference to FIG. 1, in which a printing machine 30 constructed in accordance with a preferred embodiment of the invention is illustrated in perspective. As shown therein, the printing machine 30 is a dual offset printing machine or duplicating machine which in many respects is conventional in construction. Thus, the printing machine 30 comprises a first printing head 31 which includes the usual master cylinder upon which a convention lithographic or other planogr-aphic master may be mounted. The printing head 31 further includes a blanket cylinder and an impression cylinder (the cylinders are not visible in FIGURE 1) which may be of conventional construction. An inking mechanism generally indicated by the reference numeral 33 is incorporated in the printing 'head 31 and is utilized to apply ink to a lithographic master mounted upon the master cylinder of the machine.

In the course of a printing operation, ink is applied to the master, transferred to the blanket cylinder, and printed upon a sheet of paper or the like which is passed between the blanket and impression cylinders of the printing head 31.

The paper feed mechanism 34 of the printing machine 30 is located at the right-hand side of the machine, as seen in FIGURE 1. Prefer-ably, the paper feed mechanism is of the vacuum type and is utilized to feed individual sheets of paper or the like from a stack or supply included in the paper feed mechanism. The paper feed may include an apparatus for elevating the stack of paper, as sheets are fed therefrom. The sheet feeder 34 is connected to the printing head 31 by a conveyor table 35 which may be of conventional construction and which may include suitable jogging or other aligning devices for assuring accurate alignment of the sheets of paper as they enter the printing head 31.

In addition to the main operating cylinders [and the inking apparatus 33, the printing head 31 includes certain additional operating devices which are directly employed in the printing process. Thus, the head 31 also includes a manually controlled plate-etch applicator 36 which is utilized to apply an etching solution to the planographic master on the master cylinder in printing head 31 during the initial stages of a printing run. Operation of the plate-etch applicator 36 is controlled by an operating handle 37.

As in most printing machines using planographic masters, it is necessary to apply a repellent solution to the master cylinder during the course of normal operation. For this purpose, the printing head 31 is provided with a repellent applicator 39. The device 39 affords a means for applying a repellent solution to the master cylinder, in a course of a printing operation, and for interrupting the supply of repellent solution during an automatically controlled sequence of operations.

The initial printing head 31 further includes an automatically controlled blanket cleaner 41 which is mounted upon the frame of the printing head 31 in position to engage the blanket cylinder of the first printing head. The blanket cleaner 41 is utilized to remove ink from the blanket, between individual printing operations, to permit a change in the data being printed without requiring removal of the blanket cylinder or the blanket from the printing head 31.

Primary control of the printing machine 30 is effected by means of a series of switches and other control devices mounted upon a control panel 42 on the side of the machine. Addition-al control is provided by manual controls, such as the plate etch control handle 37 and others, as described in detail hereinafter. In particular, a main control handle 43 for head 31 may be utilized to controla major portion of the machine operation whenever the automatic electrical control system of the machine is not employed. When the machine is set for automatic control, a counter is utilized to determine the length of a given printing run.

The printed sheets from head 31 are transported along a conveyor 32 to a second printing head 61. Conveyor 32, in addition to transporting the sheets between the two printing heads, turns each sheet over so that head 61 prints on the reverse side of the sheet. The turn-over conveyor is described in Patent No. 2,625,101 to H. F. Gammeter, issued January 13, 1953, to which reference maybe made for the conveyor construction and operation.

The second printing head 61 of machine 30 is in most respects a substantial duplicate of the first head 31. It includes the usual master cylinder, blanket cylinder, and impression cylinder (not visible in the drawing). An inking mechanism 63 is provided for inking a master on the master cylinder. There is a plate-etch applicator 66, controlled by an operating handle 67 that is provided with a control switch 38. Repellent solution is applied by means of a repellent applicator 69. And an automated blanket cleaner 71 is provided to clean the blanket of printing head 61. A main control handle 73 is provided for manual control of the principal machine operations, other than plate etch application.

When conditioned for automatic operation, the printing machine 30 carries out a predetermined sequence of operations based upon a very limited number of control steps performed by the machine operator. Presuming that there is an adequate supply of paper in the storage stack of the feeder 34, the operator sets the counter of the machine to print a predetermined number of sheets fed into the machine from the feeder. Thereafter, the machine operator starts the printing machine 30 in operation by actuating the switch 38 in the handle 67 of the plate etch applicator for the second printing head 61. At the same time, the operator pivots the plate etch control handles 37 and 67 from their respective normal or off positions, shown in FIGURE 1, to initiate operation of the plate etch applicators 36 and 66. Handle 37 is pivoted counterclockwise; handle 67 is moved clockwise. Plate etching is a manually controlled operation in both printing heads of the machine 30, and the number of machine cycles required to apply an etching solution to the planegraphi masters on the master cylinders mounted in the two printing heads is left to discretion of the machine operator.

After the plate etching operation, the operator releases the handles 37 and 67, which return to their initial positions as shown in FIGURE 1. When the handle 67 reaches its home position, it actuates a control switch which is effective to initiate automatic sequential operation of the printing machine 30, the sequence of automatic operations being illustrated in the timing hart, FIGURE 2. The automatic control system of the printing machine first operates to initiate application of repellent solution to the planographic masters mounted upon the master cylinders in printing heads 31 and 61. That is, the repellent solution applicators 39 and 69, which previously had not been effective to apply repellent to the masters, are actuated in the initial stage of automatic operation and are each effective to apply a repellent solution to the associated planographic master.

The next automatically controlled operation is the inking of the masters. The final form rolls of the ink trains comprising the inking systems 33 and 63 are brought into contact with the masters in printing heads 31 and 61 after the repellent solution applicators 39 and 69 have been in operation for one machine cycle. However, it should be understood that this sequence of operations may be varied to some extent, and that two or more cycles may elapse, after the repellent applicators have been actuated and before inking of the masters is initiated.

After the masters have been inked for several machine cycles, imaging of the blanket in printing head 31 is initiated. Like the other steps in operation of the machine 30, this is accomplished automatically by the control system described hereinafter. As indicated in the timing chart of FIGURE 2, five or six machine cycles are usually employed to build up an adequate ink image on the blanket before the first impression is taken, although this operation can also be adjusted. When imaging of the blankets is completed, the printing machine 30 is ready for operation and the feeder 34 is started. Actually, the feeder is started approximately three cycles before blanket imaging is completed in order that first sheet of paper will be fed into the first printing head 31 at the time that the blanket imaging operation is finished. Thus, the machine starts printing of the sheets fed from the feeder 34 and printing is continued until the automatic control system halts operation.

Imaging of the blanket in the second printing head 61 is not started at the same time as blanket imaging in the first head 31. Instead, the timing control of the present invention, described in detail hereinafter, operates to defer blanket imaging in printing head 61 for a predetermined number of machine cycles after blanket imaging has been initiated in head 31. Typically, the delay interval entailed is three machine cycles.

Each of the sheets fed from the feeder 34 Iactuates a sensing switch mounted upon the conveyor table 35 as the sheet is fed toward the printing head 31 of the machine. Ilhis switch actuates a counter for the machine which may be set by the machine operator to count a predetermined number of sheets.

When the counter completes its counting operation, that is, when the desired number of sheets have been printed, the automatic control system of the printing machine 30 stops the feeding of sheets from the feeder 34 into the first printing head 31.

After the counter counts out, imaging of the blanket in the first printing head is interrupted, as indicated in the timing chart of FIGURE 2. Interruption of the blanket imaging operation again brings the timing control of the present invention into operation. Ink transfer to the blanket of the second printing head 61 is continued, after interruption of imaging in the first head 31, for a selected number of machine cycles. Again, the delay involved may, typically, be three machine cycles.

In the next cycle of operation, inking of the masters on the master cylinders in both printing heads, by the ink mechanisms 33 and 63, is interrupted. In the next machine cycle, the repellent applicators 36 and 66 are effectively disengaged from their associated master cylinders, thereby interrupting application of the repellent solution to the planograp'hic masters. After repellent application is interrupted the blanket cleaners 41 and 71 are started in operation. Each blanket cleaner applies a cleaning solution to its associated blanket for a substantial time, which may be of the order of ten machine cycles, cleaning the blanket in preparation for the next printing operation. Thereafter, operation of the printing machine 30 is interrupted entirely, the master cylinders each being brought to rest in a home position wherein the master mounted on the cylinder may be conveniently changed by the operator. Preferably, each master cylinder is provided with a solenoid-operated master ejection device of the kind described in Patent No. 3,095,809, to H. F. Gammeter, issued July 2, 1963.

As described in the aforementioned patent of H. F. Gammeter, No. 3,056,346, the feeder 34 may include both a main stack and an auxiliary supply of sheets to be printed, the auxiliary stack being located in a separate receptacle usually referred to as a systems feeder chute. Usually, it is desirable to print all of the sheets from the systems chute before the counting operation of the counter is initiated. That is, the counter of the machine is preferably arranged to count only sheets fed from the main stack in the feeder 34. This may be accomplished, as in the printing machine of Patent No. 3,056,346, by a paper, no-paper sensing switch mounted on the systems feeder which actuates a control circuit to prevent the initiation of a counting operation by the counter until such time as the systems chute is empty. This same switch may be used to control shutdown of the machine, omitting counter control, if desired.

AUTOMATIC SEQUENCE CONTROL MECHANISM FIGURE 3 illustrates a part of the operating mechanism of the automatic sequence control used in printing machine 30 and is taken from Gammeter Patent No. 3,056,346. The operating mechanisms for printing heads 31 and 61 are substantial duplicates of each other; hence, only the sequence control mechanism 370 for printing head 31 is illustrated. The angular orientation of the control shaft 262, the shaft upon which main control handle 43 is mounted, is effective to control the application of a repellent solution to the master cylinder in printing head 31. The angular positioning of shaft 262 also controls the application of ink to the master cylinder and the transfer of the ink image from the master cylinder to the blanket cylinder. In addition, the angular orientation of the shaft 262 controlsenergization of the operating solenoids of the blanket cleaner 41 and the actuation of the sheet feeder 34 of the printing machine.

As shown in FIGURE 2, the automatic sequence control mechanism 370 comprises a ratchet member 371 which is mounted upon the control shaft 262 and which is affixed to the control shaft for rotation therewith. The ratchet 371 is provided with a series of pawl-engaging slots 372 and with a corresponding series of detent-receiving depressions 373. The slots 372 are positioned for engagement by a projection or lug 374 on a control pawl 375, whereas the depressions 373 are engageable by a detent roller 376 mounted upon a detent lever 377. The control pawl 375 is pivotally mounted upon a pin 378 which is secured to and supported by a pawl lever 379. The pawl lever 379 is mounted upon the shaft 262 for rotation with respect to the shaft. The control pawl 375 is biased for rotation in a counterclockwise direction, relative to the pin 378, by means of a spring 381 which connects the pawl to an extension portion 382 of the pawl lever 379.

Actuation of the control pawl 375 is effected by an operating linkage comprising a pawl lever operating link 384. One end 385 of the operating link 384 is eccentrically mounted upon an operating shaft 386, the shaft 386 being a shaft 'which rotates through a complete revolution during each operating cycle of the printing machine 30. The opposite end of the operating link 384 is provided with an adjustable link extension 388. The extension 388 is adjustably mounted on the end of the operating link by suitable means, such as the bolts 389, which afford a secure connection between the extension 388 and the operating link but permit adjustment of the extension longitudinally of the operating link. The extension 388 is pivotally connected to the pawl lever 379 by suitable means such as the connecting pin 391.

The pawl 37 5 is also controlled, in part, by a pawl lifting lever 692 that is pivotally mounted upon the shaft 284. One end 394 of the pawl lift lever 392 is connected by a linkage 395 to an automatic sequence control solenoid 396, the linkage 395 connecting the pawl lift lever to the armature 397 of the soleniod. The solenoid 396 is mounted upon a bracket 400 that is aflixed to a frame member 203. A spring 398 is connected to the lever 392 and to the bracket 400 and tends to bias the lever 392 toward movement in a clockwise direction about the shaft 284. Clockwise rotation of the lever 392 is limited by an adjustable stop member 399 that is mounted upon the frame member 203 in position to engage a projection 401 on the pawl lift lever.

The other end 402 of the pawl lift lever 392 is provided With an upper surface having a configuration essentially similar to the external surface of the control ratchet 371, except that the surface 403 is not provided with slots such as the slots 372. The pawl lift lever surface 403 is positioned to engage a roller 404 that is rotatably mounted upon a pin or shaft 405, the pin 405 being mounted upon the control pawl 375. The pawl lift lever surface 403 normally engages the roller 404 to prevent counterclockwise rotation of the pawl 375, but can be displaced from engagement with the roller to permit counterclockwise rotation of the pawl by pivoting the pawl lift lever 392 in a counterclockwise direction about the shaft 284.

The detent lever 377, like the lever 392, is pivot-ally mounted upon the shaft 284. A spring 406 is connected to the end of the detent lever opposite the detent roller '376, the spring 406 also being connected to a pin 407 mounted upon the bracket 400. Thus, the spring 406 biases the lever 377 toward rotation in a clockwise direction, as seen in FIGURE 2, and tends to maintain the detent roller 376 in engagement with one of the slots.

7 373 but also permits eificient counterclockwise rotation of the lever 377 to allow for re-positioning of the detent roller in the other detent slots.

In operation, the automatic sequence control mechanism 370 is effective to rotate the control shaft 262 to and through a series of four different control positions. In this regard the automatic sequence control mechanism effectively replaces the control which could otherwise be exercised by the machine operator using the handle 43.

During each cycle of machine operation, as noted herein above, the shaft 386 rotates through one complete revolution. Starting from a position shown in FIGURE 2, the rotational movement of the shaft 386 pulls the pawl lever operating link 384 to the right, pivoting the pawl lever 379 in a clockwise direction about the shaft 262. The control pawl 375, of course, moves with the pawl lever 379, on 'which it is mounted. Subsequent- 'ly, in the same cycle of machine operation, the lever 384 moves back. to the left, as seen in FIGURE 2, toward its original position. During this part of the cycle the pawl lever 379 is pivoted back in a counterclockwise direction and the control pawl 375 is again constrained to move with the lever 379. 'These reciprocating movements of the pawl lever operating link 384, the pawl lever 379, and the control pawl 375 are not ordinarily effective to change the operating condition of the printing head 31, however. The roller 404, as it rides along the surface 403 of the pawl lift lever 392, holds the control pawl 375 out of engagement with the slots 372 in the face of the control shaft ratchet member 371. Accordingly, in most cycles of machine operation, the movement of the pawl lever operating link 384,- and the consequent movement of the pawl lever and control pawl do not alter the operating condition of the printing machine.

Actuation of the automatic sequence control 370 is effected by energization of the solenoid 396. Thus, in a given cycle of machine operation, the solenoid may be energized, pulling the armature 397 upwardly as seen in FIGURE 2. As a consequence, the pawl lift lever 392 is pivoted in a counterclockwise direction about the shaft 284, against the biasing force exerted by the spring 398, moving the foot portion 402, and specifically the surface 403, of the pawl lift lever away from the roller 404 carried by the control pawl 375. During this cycle of machine operation, accordingly, the lug or extension 374 on the control pawl 375 is permitted to drop into one of the slots 372 as the conntol pawl is moved to the right by the action of the pawl lever operating link 384 and the pawl 379. During the latter part of the same cycle, when the operating linkage for the control pawl 375 is effective to move the pawl back toward the left, the engagement of the lug 374 in one of the slots 372 is effective to rotate the ratchet 371 in a counterclockwise direction to a new control position determined by engagement of the detent element 376 in one of .the depressions 373 in the ratchet. Thus, actuation of the solenoid 396 at a predetermined time relative to the cyclic operation of the shaft 396, which controls the control pawl operating linkage, is effective to cause the pawl to drive the ratchet 371, and hence the control shaft 262, in a counterclockwise direction from one operating position to another.

T o rotate the control shaft 262 in a counterclockwise direction, as described hereinabove, the solenoid 396 should be energized at a time when the control pawl 375 approaches the extreme right-hand limit of its oscillating or reciprocatory movement. The solenoid can also be used to actuate the automatic sequence control mechanism 370 to drive the control shaft 262 in a clockwise direction, however, simply by changing the timing of energization of the solenoid. Thus, the solenoid 396 may be energized with the control pawl 375 approaching or approximately located at the extreme left-hand limit of 8 its oscillating movement, this being the position illustrated for the control pawl in FIGURE 2. When this is done the lug or projection 374 on the control pawl drops into one of the slots 372. The subsequent movement of the control pawl to the right, effected by the continued operation of the shaft 386, the pawl operating link 384 and the pawl lever 379, causes the pawl to drive the ratchet 371 and rotate the ratchet and the shaft 262 in a clockwise direction. Again, and as before, the solenoid 396 is held energized for a time suflicient to rotate the ratchet 371 to bring a different one of the depressions 373 into engagement with the detent member 376 and thus locate the ratchet and the control shaft 262 in a different one of the several operating conditions for the shaft. Regardless of the direction of rotation of the shaft 262, the solenoid 396 should be deenergized before the direction of movement of the control pawl 375 is reversed in order to prevent the control pawl from simply oscillating the ratchet and the shaft 262. On the other hand, since the final position of the ratchet 371 is determined primarily by engagement of the detent member 376 in the depressions 373, the timing of energization of the solenoid 396 is not so critical as to unduly limit or complicate the operation of the automatic sequence control mechanism 370.

The automatic sequence control 370 further includes a plurality of control switches each actuated in accordance with the angular orientation of the main control shaft 262. As shown in FIGURE 4, these switches include the individual control switches 485 and 494 and a dual control switch 431 having a second switch section 490 (see FIG- URE 9). The corresponding control switches for the second printing head 61 are the switches 802, 821, 831, and 841 (FIGURES 8 and 9). The operational sequences for these switches are shown in the following table, the symbol X indicating that a switch is actuated from the condition shown in FIGURES 8 and 9 to an alternate condition.

TIMING CONTROL MECHANISM FIGURES 5, 6 and 7 illustrate a timing control or programming mechanism 200, constructed in accordance with the present invention, that is utilized to actuate the sequence control apparatus of the second printing head 61 of printing machine 30 and to render the operation of the second printing head 61 compatible with the functions performed by the initial printing head 31. As noted above, the printing head 61 is provided with a sequence control mechanism that is essentially identical with the sequence control mechanism 370 for the initial printing head 31. The timing control 200 regulates the operation of the sequence control mechanism in the second printing head so that the initial steps in the start-up sequence are performed simultaneously with the same steps in the printing head 31 but the final stage in the sequence,

. imaging of the blanket, imaging is delayed by a predetermined number of cycles to preclude excessive inking of the blanket in the second printing head prior to printing. The timing control 200 further operates to defer the interruption of blanket imaging in the printing head 61, at the end of the printing operation, to assure an adequate ink supply for the final sheets being printed.

Timing control 200 comprises a U-shaped frame 201 that is mounted within the second printing head 61 of printing machine 30. One arm 202 of the frame 201 supports a short shaft 204, the shaft 204 being supported in a suitable bearing member 205 mounted on the frame. A first sprocket or gear 206 affixed to the shaft 204; the shaft 206 is driven through one complete revolution for each cycle of machine operation. That is, sprocket 206, like the shaft 204, is rotated through a complete revolution for each revolution of the master cylinder of the second printing head. It will be recognized from the foregoing description that the master cylinders in the two printing heads must be driven in synchronism, as by a drive arrangement of the kind shown in the aforementioned Gammeter Patent No. 2,625,101.

A sprocket 207 is mounted upon shaft 204 for rotation with the shaft. The sprocket 207 is engaged by a drive chain 208 which also extends around a substantially larger sprocket 209. The sprocket 209 is mounted upon a hub 211 that is journalled upon a shaft 212 that extends across and is supported by the two arms 202 and 203 of the frame 201.

The hub 211 constitutes the initial driving element of a clutch 213 which, when engaged, affords a driving connection from the hub 211 to the shaft 212. The clutch 213 is a spring-actuated device of substantially conventional construction and is provided with a holding pin 214 that is engaged by an operating arm or lever 215. The lever 215 is a part of the armature structure of a solenoid 216, the solenoid 216 being mounted upon a bracket 217 secured to the frame 201 by suitable means such as th bolts 218.

The shaft 212 projects outwardly of both arms 202 and 203 of frame 201, thus affording two cantilever extensions for the shaft. The left-hand extension 212A of the shaft carries an indicator dial 219 having a central adjusting knob 221. The dial 219 is aligned with a fixed pointer 222 that is mounted upon the one arm 202 of frame 201. The relationship of the pointer 222 and the dial-219 is best illustrated in FIG. 7.

As shown in FIG. 5,'the right-hand cantilever extension 212B of the shaft 212 carries three cam assemblies 231, '232 and 233. The cam asembly 232, which is typical, comprises two individual cam members 234 and 235 that are secured to shaft extension 212B by suitable set screws 236 and 237 respectively. This mounting arrangement is utilized so that the two cam members 234 and 235 of the assembly can be adjusted relative to each other to provide a desired camming action and are then fixed on shaft extension 212B. A similar construction is used for each of the cam assemblies 231 and 233.

The cam assembly 231 is aligned with a first miniature control switch 241 mounted upon a switch support bracket 244 by suitable means such as a small switch bracket 245. Further control switches 242 and 243 are similarly supported upon the main support bracket 244 in alignment with the cam assemblies 232 and 233 respectively. The switch 241 is provided with a cam follower 247 that engages the cam assembly 231 so that the switch may be actuated for timed intervals in accordance with the configuration of the cam assembly. Similarly, the switches 242 and 243 are provided with the cam follower actuators 248 and 249, respectively, for actuating the switches.

FIGURE 6 illustrates the one switch 242 and the corresponding cam assembly 232 in side elevation and shows the positioning of the cam follower 248 in engagement with the cam assembly 232. With the cam members 234 and 235 adjusted, relative to each other, as illustrated in FIGURE 6, the switch 242 is maintained in one operating condition over an initial arc A of approximately 155 of rotation of shaft 212. The switch is maintained in a second operating condition over an arc B of approximately 205. The cam assembly 233 is adjusted to afford a much shorter are for the one condition, an arc of the order of 30. The cam assembly 231, on the other hand, is closed over an arc of approximately 105. The cam configurations for the assemblies 231 and 233 and their alignment relative to the cam assembly 232 are illustrated in FIGURES 6A and 6B, respectively.

In operation, the shaft 204 of the timing control 200 is rotated continuously, the shaft turning through one revolution for each printing cycle of the printing machine 30. The relative sizes of the sprockets 207 and 209 are such that sprocket 209 rotates through a complete revolution for a preselected integral number of revolutions of the shaft 204. This difierential should be related to the number of cycles of machine operation required for a sheet imprinted in the initial turning head 31 to move along the turnover conveyor 32 from the initial printing head 31 to the second printing head 61. In the form of control 200 illustrated in FIGURE 5, the drive ratio between the sprockets 207 and 209 is 6:1; that is, for each six revolutions of the shaft 204, the sprocket 209 is driven through a single revolution so as to provide adequate time delay to accommodate at least a three or four cycle time difference between the first and second heads.

Ordinarily, during operation of the printing machine, the shaft 212 is not rotated because the clutch 213 is held disengaged by the lever 215 blocking rotational movement of the holding pin 214. Upon energization of the solenoid 216, however, the lever 215 is pivoted away from the pin 214, releasing the spring actuated clutch mechanism. The pin 214 moves free of the lever 215 and the shaft 212 is driven through the clutch mechanism.

As noted above, the shaft 212 completes one revolution upon completion of six revolutions of the shaft 204. By the time the timing shaft 212 reaches its initial or home position as shown in FIGURE 5, the solenoid 212 is de energized, so that the lever 215 again engages the pin 214 and stops the timing shaft. It should be recognized that the particular clutch mechanism illustrated is not essential to the present invention and that any suitable one-revolution clutch can be employed if desired.

As the shaft 212 rotates, each of the switches 241, 242 and 243 is actuated from its normal open or off condition to a closed or on condition during a specific time interval determined by adjustment of the related cam assemblies 231, 232 and 233. These three switches control the blanket imaging operations in the second printing head 61 of the printing machine, as described more fully hereinafter in connection with FIGS. 8 and 9.

The dial 219 and the pointer 222 are provided for manual adjustment of the initial position of the shaft 212. Initially, the dial 219 is adjusted so that the zero indication on the dial is aligned with the pointer 222. In normal machine operation no further adjustment is required. If it happens that the pringting machine is cut off during a time interval in which the shaft 212 is in operation and hence rotated away from its zero or home position, subsequent operation of the machine would begin with the timing shaft starting from an erroneous position and would result in incorrect timing of the sequential operation of the second printing head. This is simply and easily prevented by manually adjusting the shaft to bring the zero position on the dial 219 back into alignment with the pointer 222 before machine operation is resumed.

ELECTRICAL CONTROL CIRCUITS FIGURES 8 and 9, in combination, illustrate the electrical control circuit for the printing machine 30. This circuit comprises a pair of electrical supply lines or busses 410 and 411 which are connected to a suitable A.C. supply by means of a conventional supply circuit (not shown) which may include a main switch and the usual overload protection.

The control circuit includes a drive motor relay DMR having an operating coil 413, two pair of normally open contacts 414 and 415, and a pair of normally closed contacts 417. The main drive motor 416 of the printing machine, which drives both of the printing heads 31 and 61,

1. 1 is connected across the busses 41!) and 411 in a circuit that includes, in series, the normally open contacts 414 of the relay DMR. Contacts 414 also connect the bus 410 to an auxiliary bus 429.

One terminal of the operating coil 413 of the relay DMR is connected directly to the main bus 411. The other terminal 418 of the relay coil is connected through a series circuit comprising a stacker end stop switch 420, a stop switch 421, and a start switch 419 to conductor 422. The normally open contacts 415 of the relay DMR are connected in parallel with the machine start switch 419 to afford a holding circuit for the relay. The main energizing circuit is completed from the conductor 422 through a pair of normally closed relay contacts 425 back to the other main bus 410.

The contacts 425 are incorporated in a control relay CR2 having an operating coil 423; this relay also includes a pair of normally open contacts 424. One terminal of the operating coil 423 of this relay is connected through the relay contacts 424 to auxiliary bus 434), the auxiliary bus 430 being connected back through the sequence start switch 230 to the main terminal 437 of the start and stop switches 419 and 421.

The control relay CR2 operates in conjunction with a time delay relay TDRI having an operating coil 428- and two pair of normally open contacts 426 and 427. The delay circuit of the relay TDRI is not illustrated, having been omitted from the drawing to avoid confusion and overcrowding. This is also true of the other time delay relays illustrated in FIGS. 8 and 9. These time delay relays are essentially conventional in construction and any suitable time delay circuit may be employed. Each of the delay relays is provided with one or more potentiometers or other suitable means for adjusting the delay interval required for the relay to return to its normal or unactuated condition upon de-energization of the relay, such adjustment devices being well-known and hence requiring no illustration.

The contacts 426 of the time delay relay TDRl are connected in parallel with the contacts 424 of the control relay CR2. The contacts 427 of the time delay relay TDRl are connected in parallel with the control relay contacts 425. One terminal of the operating coil 428 is connected directly to the main bus 411. The other terminal of this coil is connected through a pair of normally open relay contacts 489 and through two switches 801 and 802 back to the auxiliary bus 430. The contacts 489 constitute a part of a further time delay relay TDR4 described more fully hereinafter. The cylinder stop conditioning switch 801 is a cam-actuated switch that is controlled by a cam operated in time with the printing cylinder of the first head, and designed to insure that TDRl starts decaying at the same relative cylinder position for each printing operation. The cylinders then stop in the same position after each printing operation. The switch 802 is a cam-actuated switch controlled by a cam on the main sequence control shaft of the second printing head 61, and corresponds to one of the similar switches for the initial printing head as illustrated in FIG. 3. The switch 802 is in the position shown in FIG. 8 when the main control shaft of the second printing head is in its zero or home position but is actuated to its alternate position whenever that shaft is in any of its one, two or three control positions.

One of the principal control elements of the operating circuit for printing machine 30 is a four-pole doublethrow switch 433 comprising individual switch sections 432 (FIG. 9), 434, 435 and 436 (FIG. 8). The conductor 422 in the energizing circuit of the drive motor relay DMR is connected through a cam controlled switch 431 and through one section 432 of the switch 433 to the common terminal 437 of the start and stop switches by means of a circuit that also includes, in series, the push button safety switch 38 in the handle 67 of the plate etch applicator (FIG. 1) and a starting switch 227 that is actuated by movements of the plate etch applicator handle. The four-section ganged switch 433 is utilized to actuate the control circuit from a manual control condition to an automatic control condition, all sections of the switch being shown in the automatic position. The switch 431 is one of the cam controlled switches actuated by the main control shaft 262 of the first printing head 31 (see FIG. 4). This particular switch is in the position shown in the drawing when the main control shaft of the initial printing head is in its zero or home position but is closed upon an alternate terminal 506 whenever the shaft 262 is in any of its operating positions one, two and three.

The operating circuit of the printing machine 30 further includes a counter 44 having a reset coil 438 and a count coil 439. The counter 44 further includes two pair of normally open contacts 441 and 442 and a pair of normally closed contacts 443. The construction of the counter is such that all of the contacts 441-443 are held open Whenever the reset coil 438 is energized. When the reset coil is de-energized, these contacts assume the conditions indicated in the drawings. When the counter has completed a counting operation, the contacts 441 and 442 close and the contacts 443 open.

One terminal of each of the counter operating coils 438 and 439 is connected directly to the main operating bus 411. The counter coil 439 is connected in an energizing circuit that includes, in series, a count pulse switch 46, a counter on-off switch 452, and one section 449 of a four-pole double-throw switch 446. From switch 449, this circuit extends through a paper-no paper switch 103 in FIG. 9 to a pair of normally open contacts 457 in a control relay CR7 (FIG. 8) and then from the contacts 457 back through a machine start switch 464 to the secondary bus 429.

In this circuit for the count coil 439, FIG. 9, the switch 46 is located upon the conveyor table 35 that feeds paper into the initial printing head of the printing machine 30, being positioned to count each sheet of paper fed to the printing machine. That is, the switch 46 is actuated from its normal closed position to its open position by each sheet of paper fed into the printing machine. The switch 452 is located on the main control panel 42 of the printing machine 30 (see FIG. 1). The four-pole double-throw switch 446 is employed to switch the control circuit between a first operating condition in which machine operation is interrupted in response to the counting of a predetermined number of sheets fed through the machine by the counter 44 and an alternate operating condition in which machine operation is interrupted by completion of feeding of sheets from the systems chute of the sheet feeder. The switch is shown in its counteroperation position. The paper, no-paper switch 103 is mounted on the systems feeder chute of the printing machine and is closed only when the systems chute is empty.

One of the contacts of the normally open pair 441 in the counter 44 is connected to the normally open pole 804 of the switch 802 (FIG. 8). This same contact is connected to a second section 445 of the system-counter control switch 446, switch section 445 being open-circuited for counter control operation but being closed for system operation. The other contact of pair 44 is con nected to one terminal of the operating coil 488 of the time delay relay TDR4, the remaining terminal of that coil being connected directly to the main bus 411. The same contact of the pair 441 is also connected to the operating coil 896 of a control relay CR11, the other terminal of the coil 806 being returned to the bus 411. A pair of normally open contacts 808 of an additional control relay CR9 are connected from the switch section 445 to the counter contacts 441 so that the contacts 808 are in parallel with the contacts 441 when the switch section 445 is in its system position.

The control circuit includes a further time delay relay TDR6 (FIG. 9) having an operating coil 461 and a pair of normally open contacts 465. One terminal of the operating coil 461 is connected to the normally closed contact pair 443 in the counter 44. From the contact pair 443, this circuit extends to a pair of normally open contacts 456 in the control relay CR7 (FIG. 8) and from the contacts 456 through a feeder stop switch 463 and the feeder start switch 464 to the secondary bus 429.

One contact of the normally open contact pair 465 of delay relay TDR6 (FIG. 9) is connected through the normally closed contacts 417 of the relay DMR to the conductor 422 in the energizing circuit for the drive motor. This same contact of the pair 465 is connected to the counter pole of an additional section 447 of the switch 446. From the switch section 447 this circuit extends to one terminal of a vacuum valve solenoid 466, the other terminal of the solenoid being connected to the main bus 411. The system terminal 467 of the switch section 447 is connected to the terminal 468 of the paper, nopaper switch 103.

The other contact of the contact pair 465 in the relay TDR6 is connected to the normally open contact 506 of the cam-actuated control switch 431. The contact 586 is connected through the normally open contacts 442 of the counter 44 to one section 435 of the manual-automatic switch 433. Switch section 435, and specifically the automatic terminal thereof, is connected to a pawl pulse switch 472 that is actuated for a specific time interval during each cycle of machine operation. The same terminal of the switch 472 that is connected to the switch section 435 is also connected to the system terminal of an additional section 448 in the system-counter control switch 446. j

The control relay CR9, in addition to the normally open contacts 808 mentioned above, is provided with an operating coil 809 and a further set of normally open contacts 811. The normally open contacts 811 are connected in series in a circuit that extends from the switch 448 back to the terminal 506 of the control switch 431. The operating coil 889 of the relay CR9 has one terminal connected directly to the main bus 411. The other terminal of this control relay, which functions only for system-stop operation, is connected to the section 449 of the system-counter control switch 446.

. At the right-hand side of FIG. 9, near the top of the figure, there are shown two solenoids 812 and 813, each having one terminal connected to the main bus 411. The solenoids 812 and 813 are utilized to actuate ejector mechanisms on the printing heads 31 and 61, respectively, of the printing machine 30. The master ejector mechanism is of particular value in short run systems work; it constitutes an apparatus for ejecting the master from the clamp on the master cylinder, freeing the master for prompt removal and replacement by the machine operator. As previously noted, master ejection devices of this kind are described in Patent No. 3,095,809.

The master ejector solenoid 812 for the first printing head 31 of the printing machine is connected through a switch 814 to a main master ejection switch 815. The solenoid 813 for the second printing head is similarly connected through a switch 816 to the switch 815. The switch 815 is connected in a manual operating circuit, by means of a conductor 817, to a manual control switch 818 shown in the lower left-hand corner of FIG. 9, the switch 818 being connected back to the manual terminal of switch section 432.

The switch 815 in the operating circuit for the master ejector solenoids is also connected through a cam-actuated control switch 490 to the timing control switch 241. Switch 490 is actuated by the main control shaft 262 for the first printing head 31 and is closed only when the shaft 262 is in its initial or zero position. Switch 241, which is a part of the timing control 200 (see FIG. is connected back to the auxiliary bus 430.

The pump motor 481 for the printing machine 30 is shown in the lower right-hand corner of FIG. 8. One

terminal of the motor is connected to the main bus 411 and the other terminal is connected to the main bus 410 through a circuit that includes, in series, a pair of normally open contacts 479 in a pump motor control relay PMR. In addition to the normally open contacts 479, the relay PMR includes an operating coil 477, a further pair of normally open contacts 478, and a pair of normally closed contacts 480.

One terminal of the operating coil 477 of the relay PMR is connected directly to the main bus 411. The other terminal of the coil is connected to one pole of a doublepole double-throw pump motor switch 462. In the position shown, this pole of the switch 462 is electrically connected to the conductor 422 in FIG. 9. With the switch 462 in its alternate condition, the pump motor relay coil is connected to the feeder stop switch 463.

Each of the contact pairs 478 and 480 in the relay PMR is connected to the auxiliary bus 429. The normally closed contact pair 480 is connected from the secondary bus 429 to the reset coil 438 of the counter 44 (FIG. 9). The normally open contact pair 478 connects the auxiliary bus 429 to the normally open contacts 457 in the control relay CR7 and to a pair of normally closed contacts 459 in the same relay. In addition, a connection is provided from the contact pair 478 to a camactuated control switch 494 in the energizing circuit for the operating coil 491 of a time delay relay TDRS, the other terminal of the coil 491 being returned to the main bus 411. The switch 494 is one of the control switches that is actuated in accordance with the position of the main control shaft 262 of the initial printing head 31 of the machine (see FIG. 4), being actuated from the illustrated position to its alternate position whenever the shafts is in its zero, one and two positions.

The time delay relay TDR4 (FIG. 8) in addition to the coil 488 and the contact pair 489, is provided with a further set of normally open contacts 509. One side of the contact pair 509 is connected to the cylinder stop condition switch 801. The other side of this contact pair is connected to the blanket cleaner solenoids 341, 342, 343 and 344 that actuate the blanket cleaners for both of the printing heads of the machine 30. Provision is also made for manual control of the blanket cleaner solenoids, these solenoids being connected back to the auxiliary bus 429 through a manual blanket cleaner control switch 487.

The control relay CR7, shown at the top center of FIG. 8, is provided with an operating coil 455 having one terminal connected directly to the main bus 411. The other terminal of the coil 455 is connected to pole 436 of the manual-automatic control switch 433. With the switch in its automatic position, as shown, the control relay coil is connected through switch section 436 back to the paper-no paper switch 103 (FIG. 9). It the switch is thrown to the manual position, the coil is connected back through switch section 436 to the terminal 418 (FIG. 9).

Another time delay relay TDR3 is incorporated in the control circuit for the printing machine, this relay being provided with an operating coil 482, a pair of normally open contacts 483, and a pair of normally closed contacts 500. One terminal of the relay coil 482 is connected directly to the main bus 411. The other terminal of the coil is connected through a cam-controlled switch 486 to the normally closed contacts 459 in the control relay CR7. The switch 486 is one of the cam-actuated switches that is controlled by the position of the main control shaft 262 in the initial printing head 31 of the machine (see FIG. 4). It remains in the illustrated position whenever the control shaft is in its two and three positions but is actuated to an alternate pole 486 whenever the shaft 262 is in its zero or one positions. The terminal 486 is connected through the normally closed contacts 500 of the relay to the pawl pulse switch 472. The left-hand terminal of the relay coil 482, as

15 seen in FIG. 8, is connected to the pawl pulse switch 472 through the normally open contacts 483 of the relay.

The pawl pulse switch 472 is utilized to control the pawl solenoid 396 that actuates the control mechanism 370 for the main control shaft 262 of the initial printing head 31 of the printing machine (see FIG. 3). Thus, the pawl pulse switch 472 is connected to one terminal of the pawl pulse solenoid 396, the other terminal of the solenoid being returned to the main bus 411.

The pawl pulse switch 472 is also connected to a cam-actuated control switch 821. Switch 821 is a camactuated switch controlled in accordance with the position of the main control shaft for the second printing head of the machine; the switch remains in the illustrated position (FIG. 8) whenever the main control shaft of the second printing head is in its two and three positions but is actuated to its alternate condition whenever that shaft is in its zero or one positions. Switch 821 is connected through a pair of normally closed contacts 822 in a control relay CR10 to one terminal of the pawl pulse solenoid 896 for the second printing head. Solenoid 896 corresponds to the solenoid 396 except that it is in the second head of the printing machine rather than the first head.

The control relay CR10, in addition to the normally closed contacts 822, comprises an operating coil 823 and two sets of normally open contacts 824 and 825. This control relay operates in conjunction with the control relay CRll, the latter relay comprising two sets of normally closed contacts 826 and 827 and two sets of normally open contacts 828 and 829.

The normally open contacts 825 of the relay CR10 are connected in an energizing circuit for the clutch solenoid 216 of the timing control 200 (FIG. Thus, one terminal of the solenoid 216 is connected directly to the main bus 411 and the other terminal is connected through the contacts 825 to the auxiliary bus 429. The operating coil 823 for the relay CR1!) has one terminal connected directly to the bus 411. The other terminal of the coil is connected through the normally open contacts 828 of the relay CR11 to the auxiliary bus 429. In addition, there is a circuit connection from the contacts 828 through a cam actuated control switch 831 and through the normally closed contacts 826 of the relay CR11 back to one pole of the pump motor switch 462. This pole of the pump motor switch is connected in series with the feeder solenoid 133 for the printing machine, the other terminal of the solenoid 133 being connected to the main bus 411. A blower solenoid 133A is connected in parallel with the solenoid 133.

Returning to the control relays CR and CR11, FIG. 8, it is seen that the pawl solenoid 896' is connected through the normally open contacts 824 of the relay ORIO to the contact pairs 827 and 829 in the relay CR11. The normally closed contact pair 827 continues this circuit to the cam actuated control switch 243 of the timing control 200 (see FIG. 5), the switch 243 being returned to the auxiliary bus 430.

The remaining contact of the pair 829 is connected to a cam actuated control switch 841, this switch being controlled in accordance with the operating position and main control shaft for the second printing head of the machine. Switch 841 remains in the illustrated position only when the main control shaft of the second printing head is in its three position being actuated to its alternate condition whenever that shaft is in any of its other three operating positions. With the control shaft of the second printing head in its three position, the switch 841 connects the relay contacts 829 to the camactuated. control switch 242 in the timing control 200. The switch 242 is returned to the auxiliary bus 430. In this alternate position, the switch 841 connects the contact pair 829 to a reverse step pulse switch 473 that is closed once during each cycle of the machine operation.

Returning to the time relay relay TDRS, it is seen that this relay utilizes a single pair of normally closed contacts 492. One contact of pair 492 is connected to the normally open contacts 457 in the control relay CR7. The other contact in this pair is connected to the terminal 497 of the switch 494. In addition, the contact 497 is connected back to the pump motor switch 462.

The control circuit of FIGURES 8 and 9 is shown with the switches adjusted for automatic control of the printing machine 30 under the control of the counter 44. The operator starts the printing machine by pressing the pushbutton 38 in the handle 67 of the plate etch applicator 69, (see FIG. 1) for the second printing head 61. The handle 67 is pulled downwardly by the operator, closing the plate etch switch 227 (FIG. 9). At the same time, the operator actuates the handle 37 to begin the plate etch operation on the first head 31 of the printing machine.

With switches 227 and 38 closed, the drive motor relay DMR is energized through a circuit including, in series, the main bus 411, the relay coil 4 13, the stop switches 420 and 421., the switches 38, 227, 432, and 431, the conductor 422, the normally closed contacts 425 of the relay CR2, and the other main bus 410. If, for any reason, the printing machine is to be started without operation of the plate etch applicators, the drive motor relay DMR can be energized by the operator by closing the machine start switch 419, which by-passes all of the switches 38, 227, 432 and 431.

When the relay DMR is energized, its normally open contacts 415 are closed, establishing a holding circuit for the relay through the stop switches 420 and 421 and the normally closed contacts 425 of the relay CR2. The contacts "417 are opened for a purpose described hereinafter. Moreover, the contacts 414 are closed, completing an operating circuit for the main drive motor 416 of the printing machine. The drive motor 416 is connected, through suitable mechanical drive linkages, to both printing heads 31 and 6 1 of the printing machine 30, and initiates cyclic operation of the major printing machine components, including particularly the main cylinders, in both printing heads. In addition to establishing an operating circuit for the drive motor 416, the closing of the contacts 414 in the relay DMR connects the main bus 410 to the auxiliary bus 429, thereby energizing the auxiliary bus throughout .the remainder of the period of machine operation.

When the printing machine is started, the reset coil 438 of the counter 44 is energized through a circuit starting at the main bus 411 and extending through the reset coil 438 and the normally closed contacts 480 of the pump motor relay PMR to the auxiliary bus 429. With the reset coil 438 thus energized, the counter contacts 441 and 442 remain open and the normally closed contacts 443 are held open as described hereinabove.

The duration of the plate etching operation, initiated as described above, is controlled manually by the machine operator. When the initial etching operation is completed, the control handles of both plate etch applicators are returned to their normal positions. The return of the control handle 67 of the plate etch applicator in the second printing head 61 to its initial position closes the sequence starting switch 230 as described in the aforementioned Gammeter Patent No. 3,056,346. Upon closing of the switch 230, the operating coil 477 of the pump motor relay PMR is energized through a circuit beginning at main bus 411 and extending through the coil 477, the pump motor switch 462, the sequence stop switch 463, section 434 of the manual-automatic control switch 433, the auxiliary bus 430, the switch 230, the DMR relay contacts 415, the normally closed contacts 425 of the relay CR2, and the main bus 410. Alternatively, if the machine is to be started without using the plate etch applicators, the pump motor relay PMR may be energized through a parallel circuit comprising the switch 462, the stop switch 463, and the feed start switch 464.

Upon energization of the relay PMR, the contacts 479 are closed, completing an energizing circuit for the pump motor 481 between the two main busses 411 and 410. With the pump in operation, a vacuum is built up to provide for subsequent operation of the sheet feeder 34 (-FIG. 1). The contacts 478 of the pump motor relay are also closed, completing a holding circuit for the relay that begins at the auxiliary bus 429 and extends through the contacts '478 to the stop switch 463 and then back through the pump motor switch 462 to the coil 477. It should be noted that, as long as the pump motor relay PMR remains energized, the conductor 5 is maintained at the same operating potential as the main bus 410, through its connection to the auxiliary bus 429. I

When the printing machine is placed in operation, the two main control shafts for the printing heads 31 and 61 are each in their initial or zero position. The switch 494, which is controlled by the position of the shaft 262 in the first printing head 31, is accordingly closed upon that switch terminal which is connected to the operating coil 491 of the time delay relay TDRS. Consequently, upon energization of the pump motor relay PMR and the closing of the contacts 478, with the resultant energization of the conductor 510 at ,the same operating potential as the main bus 410, the relay TDRS is energized. This causes contacts 492 to open; these contacts are subsequently closed to energize the blower and feed solenoids 133A and 133 as described hereinafter.

With the control shaft 262 in its zero position, the switch 485 (FIG. 8) is closed upon that switch terminal that is connected to the operating coil 482 of the relay TDR3. Accordingly, the relay TDR3 is also energized through a circuit extending from the main bus 411 through the coil 482, the switch 485, and the normally closed contacts 459 of the relay CR7 to the conductor 510. With the relay energized the contacts 483 are closed, completing a circuit from the conductor 510 to the pawl pulse switch 473. In this position of the main contro shaft of the first head, the switch 431 (FIG. 9) remains in its illustrated position. The switch 490 is closed, but this action is of no particular significance at this point in the operating sequence.

For the zero position of the main control shaft of the second printing head, the switch 821 is closed, enabling the completion of an energizing circuit for the pawl solenoid 896 as described hereinafter. The switch 831 remains closed, as illustrated. The switch 802 is in the position shown in the drawings (FIG. 8). The switch 841 is actuated to its alternate position from that shown in the drawing but does not affect operation of the system at this point because it is open-circuited at the contacts 829 of the relay CR11.

During the first cycle of machine operation following actuation of the pump motor relay PMR the pawl pulse switch 472 is actuated for a short time interval, closing upon that switch terminal connected to the contacts of the relay TDR3. This switch is closed during a corresponding time interval in each cycle of machine operation, and is also closed upon its alternate terminal during a different time interval in each cycle. Upon actuation of the pawl pulse switch into engagement with the terminal connected to the contacts 483, an energizing circuit is established for the pawl solenoid 396 in the first printing head 31 of the machine. This circuit extends from the main bus 411 through the solenoid 396 to the switch 472 and then through the contacts 483, the switch 485, and the normally closed contacts 459 of the relay CR7 to the conductor 510. Energization of the pawl solenoid 396 actuates the automatic sequence control mechanism 370 for the first printing head, described hereinabove, and drives the main control shaft 262 of the first printing head from its zero position to its one position. This movement of the control shaft initiates the application of repellent solution to the master cylinder in the first printing head 31.

At the time that the pawl solenoid 396 for the first printing head is energized, the corresponding pawl solenoid 896 for the second printing head is also energized. The circuit extends through the normally closed contacts 822 of the relay CR1!) through the switch 821 to the pawl pulse switch 472. Accordingly, the control shaft in the second printing head is also stepped from its zero position to its one position.

Advancement of the control shafts of the two printing heads to their one positions effects certain changes in the control circuit of FIGS. 8 and 9. The switches 485 and 494 (FIG. 8) remain in the same conditions as for the zero position of the control shaft that actuates them. The switch 431 (FIG. 9), however, is now actuated to its alternate position, closing upon the terminal 506. This connects the conductor 511 connected to terminal 506 to the conductor 422 and back through the contacts 425 of the relay CR2 to the main bus 410. For the present, however, this has no effect upon machine operation because the operating circuits from the conductor 511 are all open, the counter contacts 442 and the contacts 465 of the relay 'TDR6 presently being open. The switch 490 is also opened, but this has no significance at this point in the operating sequence.

The switches 821, 831 and 841 actuated by the second head control shaft do not change in operating condition with the stepping of that control shaft to its one position. Switch 802 (FIG. 8) is actuated, closing upon its contact 804 and connecting the conductor 510 to the terminal 884. Again, however, there is no immediate change in control action, since the circuits from the terminal 804 are open at the contacts 441 and the switch 445 in FIG. 9.

In the next cycle of machine operation, the two pawl solenoids 396 and 896 are again energized by the closing of the switch 472, so that the two control shafts in the printing heads are stepped from their one position to their two positions. This results in no change in the operating connections for the switches 494, 431 and 490 controlled by the main control shaft in the first printing head. Furthermore, the switches 802, 831 and 841 actuated by the second head control shaft remain unchanged.

The stepping of the control shaft 262 of the first printing head to its two position, however, actuates the switch 485 to its alternate position close upon the terminal 486. This opens the operating circuit for the coil 482 of' the time delay relay TDR3. The relay is not immediately changed in its operating condition, however, due to the time delay operating characteristics of the relay. The previous connection to the pawl pulse switch 472 through the contacts 483 is now open at the switch 485, and the contacts 500 have not yet closed. Consequently, on succeeding cycles of operation, the pawl solenoid energizing circuit cannot be completed through the pawl pulse switch 473 until such time as the delay interval for the relay TDR3 passes and the contacts 500 I reclose.

The movement of the second head control shaft to its two position is effective to open the control switch 821 (FIG. 8). Consequently, it is no longer possible to energize the second head pawl solenoid 896 through the same circuit as the first head pawl solenoid 396.

The control shafts for both of the printing heads remain in their respective two positions until the time delay relay TDR3 times out. After this time delay interval, the contacts 500 close, completing a connection from the conductor 518 through the contact 459 on the relay CR7, the switch 485, and the contacts 500 to the pawl pulse switch 473. Consequently, in the next cycle of machine operation, when the pawl pulse switch 473 is actuated to close on the terminal connected to the contacts 500, the pawl solenoid 396 is energized and advances the main control shaft 262 of the mechanism 370 to its final or three position. It should be noted that the pawl 19 solenoid 896 for the second printing head is not energized and that the control shaft in the second head remains in its two position.

Advancement of the main control shaft for the number one head to its three position makes no change in the switches 431, 485 and 490. The switch 494, however, is now actuated to close upon the terminal 497. This action of the switch 494 is effective to de-energize the time relay TDRS; however, the contacts 492 do not close immediately because of the delay characteristics of the relay.

Actuation of the switch 494 into engagement with the switch terminal 497 also produces several other actions in the control circuit. An energizing circuit is now completed from the conductor 510 through the switch 497 and the pump motor switch 462 to the feed and blower solenoids 133 and 133A in the sheet feeder mechanism of the printing machine. A connection is also completed from the conductor 510 through the switch 494, the normally closed contacts 826 of the relay CR11, the switch 831 (now closed), and the coil 823 to the main bus 411. Accordingly, the coil 823 is energized, actuating the contacts 824 and 825 of the relay CR10 to closed condition and opening the relay contacts 822. The closing of the contacts 825 completes a connection from the auxiliary bus 429 through the clutch coil 216 of the timing mechanism 200 (FIG. to the main bus 411. The opening of the contacts 822 precludes energization of the pawl solenoid 896 through the switch 821 in a subsequent portion of the cycle. The closing of the contacts 824 sets up an operating circuit that goes into effect at a later time.

As noted above, a predetermined time interval after the main control shaft of the first printing head reaches its three position, the contacts 492 of the relay TDRS, now de-energized, reclose. Upon the closing of these contacts, an operating circuit is established to energize the control relay CR7. This circuit extends from the conductor 510 through the switch 497, the contacts 492, the manual-automatic switch section 436, and the relay coil 455 to the main bus 411. The closing of the contacts 492 also establishes an operating circuit for the counting coil 439 of the counter 434 (FIG. 9). Beginning in FIG. 8, with the conductor 510, this circuit extends through the switch 494, the contacts 492, the switch 193 (FIG. 9), the system-counter switch section 449, the switch 452, and the count pulse switch 46 to the coil 439 and thence directly to the bus 411. The switch 46 closes once each time a sheet is fed into the machine from the feeder 34. Consequently, the counter 439 is now conditioned to count the sheets fed through the printing machine.

Energization of the relay CR7 (FIG. 8) closes the contacts 456 and 457 and opens the contacts 459. The closing of the contacts 457 of the relay establishes a holding circuit for the relay coil 455 so that the relay may be maintained in energized condition at a subsequent stage of the sequence of operations when the switch 494 is opened. The contacts 459 are opened so that the time delay relay TDR3 will not be energized in the sequence of control operations that occurs upon completion of a printing operation. Closing of the contacts 456 is effective to energize the time delay relay TDR6 (FIG. 9). The operating circuit for this time delay relay, starting at the conductor 5'10, in FIG. 8, extends through the feeder stop switch 463, the contacts 456, the normally closed contacts 443 of the counter 44 (FIG. 9) and the operating coil 461 of the relay to the main bus 411.

Energization of the time delay relay TDR6 closes its contacts 465. This completes an operating circuit for the vacuum valve solenoid 466. Starting at the bus 411, this circuit extends through the solenoid 466, the systemcounter switch section 447, the contacts 465, the switch 431 (now closed at terminal 506), the conductor 422, and the normally closed contacts 425 of the relay CR2 to the other main bus 410. The feeder and blower solenoids 133 and 133A have previously been energized, as has the pump motor 481, described above. Consequently upon energization of the vacuum valve solenoid 466, the feeder is in operation and the feeding and printing of sheets begins.

Like the printing head 31, the second printing head 61 must have its control shaft in the three position to go forward with a printing operation. As noted above, both the pawl solenoids 396 and 896 (FIG. 8) are actuated simultaneously in advancing the control shafts to their respective two positions, but the pawl solenoid 896 is not energized when the solenoid 396 is actuated to bring the control shaft of the first printing head to its ultimate printing position.

The clutch solenoid 216 of the timing control 200, however, is enegized at the time that the control shaft of the first printing head advances to its three position, as described above. From that point in time onward, the shaft 212 of the timing control (FIG. 5) is rotated. After three machine cycles have transpired, the forward step pulse switch 243 of the timing control 200 is closed.

When the switch 243 closes, the pawl solenoid 896 (FIG. 8) is energized through a circuit that begins with the bus 411 and extends through the solenoid 896, the contacts 824 of the relay CR10 (now closed), the normally closed contacts 827 of the relay CR1, and the program switch 243 to the auxiliary bus 430, which is connected to the conductor 510 through the switch section 434. Energization of the solenoid 896 advances the control shaft of the second printing head to its three position, enabling the printing head 61 to proceed with imaging of the blanket cylinder and printing of the sheets as they are fed to the second printing head from the first printing head (see FIG. 2).

When the main control shaft of the second printing head reaches its three position, the switches 802 and 821 (FIG, 8) do not change in operating condition. The switch 831 is opened, deenergizing the control relay CR10. As a consequence, the contacts 825 of the relay are opened, de-energizing the clutch solenoid 216, and stopping operation of the timing control 200 by disengaging the clutch 213 (FIG. 5). Furthermore, the switch 841 is actuated and closes on the terminal of the switch that is connected to the reverse stepping switch 242, conditioning the control system for the reverse or shut down sequence of operations described hereinafter.

Once printing in both heads 31 and 61 has been initiated, as described above, it continues uninterrupted until the predetermined number of sheets set in the counter 44 has been counted by the actuation of count pulse switch 46 and the consequent energization of the count coil 439. The next significant control operation is the counting out of the counter 44; when this occurs, the contacts 442 and 441 close and the contacts 443 open.

The opening of the contacts 443 opens the energizing circuit for the time delay relay TDR6. This produces no immediate control effect since the relay contacts 465 remain closed during the delay interval that has been established for the relay. When the relay TDR6 has timed out, the contacts 465 open, de-energizing the vacuum valve solenoid 466.

The closing of the counter contacts 442 completes an energizing circuit from the conductor 411 through the contacts 442 of the switch section 435 to the pawl pulse switch 472 (FIG. 8). It should be noted that the subsequent effective operation of the pawl pulse switch 472 will occur in a different part of the machine cycle than heretofore described, it being necessary to energize the pawl solenoid 396 at a different time in each machine cycle in order to step the main control shaft of the first printing head back to its original or zero position.

On the next cycle of machine operation following the counting out of the counter 44, the pawl solenoid 396 is energized through a circuit beginning at the bus 411 and extending through the solenoid and through the switches 472 and 435 and the relay contacts 442 to the conductor 511, which is maintained at the potential of the bus 410, through the switch 431 (FIG. 9) as described above. Consequently, the main control shaft 262 for the initial printing head is drawn back from its three position to its two position. At this point, however, the corresponding control shaft for the second printing head is not changed and remains in its three or printing position.

The closing of the contacts 441 in the counter 44 energizes both of the relays CR11 and TDR4. In each instance, the circuit extends from the bus 411 in FIG. 8 through the relay coil to the counter contacts 441 in FIG. 9; from the counter contacts the circuit continues through switch 802 (now closed on contact 804) and through the switch section 434 to the conductor 510.

Upon energization of the control relay CRll, the contacts 826 and 827 are opened and the contacts 828 and 829 are closed. The closing of the contacts 828 establishes an energizing circuit for the relay CR10. This circuit, beginning at the bus 411, extends through the relay coil 823 and the contacts 828 to the auxiliary bus 429.. The closing of the contacts 829 establishes an energizing circuit for the pawl solenoid 896 of the second printing head, as described more fully hereinafter. The opening of the contacts 827 removes the forward pulse switch 243 of the program mechanism 200 from the operating circuit of the solenoid 896. The opening of the contacts 826 insures against completion of an undesired circuit to the control relay CR when the control shaft of the second printing head later is returned to its two position.

The initial significant action of the control system, upon completion of the counting of the desired number of printed copies, is the actuation of the control mechanism for the first printing head that-returns the main control shaft 262 to its two position, as described above. This produces no change in the operating conditions for the switches 431, 485 and 490. The switch 494 (FIG. 8), however, is returned to that position in which it is connected to the operating coil 49-1 of the time delay relay TDRS. Consequently, this relay is again energized and its contacts 492 are opened. The control relay CR7 remains energized, through its own contacts 457 and the manual-automatic switch section 436. But the solenoids K133 and 133A are de-energized, interrupting the feeding of paper into the machine.

On the next cycle of machine operation, the pawl pulse switch 472 again energizes the solenoid 396 to drive the control shaft for the initial printing head from its two position to its one position. This movement of the control shaft makes no effective change in the operating conditions for the switches 491, 490 or 494 actuated by the shaft. In this instance, however, the switch 485 (FIG, 8) returns to engagement with the switch terminal connected to the operating coil 482 of the time delay relay TDR3. But the relay TDR3 is not energized because the relay CR7 remains energized and its contacts 459 are open.

In the next cycle of machine operation, the pawl pulse switch 472 again energizes the solenoid 396 to drive the main control shaft of the. first printing head back to its initial or zero position. This produces no change in the operating conditions for the switches 485 and 494 (FIG. 8). The switch 498 (FIG. 9) is closed, preparatory to energization of the master ejector solenoids 812 and 813. Moreover, the switch 586 is returned to its initial illustrated position.

The actuation of the switch 431 opens the operating circuit, extending through the counter contacts 442 and the pawl pulse switch 472, through which the pawl solenoid 396 was energized on the preceding three cycles. This prevents further energization of the pawl solenoid 396, which would serve no useful purpose. At the same 22 time, the operating circuit for the vacuum valve solenoid 466 is opened at the switch 431.

As noted above, the control relay CR10 was energized in the same cycle of operation in which the reverse sequence movements of the control shaft for the first printing head 31 were initiated. At that time, the consequent closing of the relay contacts 825 were effective to energize the clutch solenoid 216 of the program mechanism 200.

Some three machine cycles later, the switch 242 in the program mechanism 200 (FIGS. 5 and 9) is closed. When this occurs, the pawl solenoid 896 for the second printing head (FIG. 8) is energized through a circuit extending from the bus 411 through solenoid 896, relay contacts 824 and 829, and switches 841 and 242 to the conductor 430, connected through the switch section 434 to the conductor 510. Accordingly, some three machine cycles after the first printing head 31 has its main control shaft 262 driven back to its two position, the control shaft of the second printing head 61 starts its reverse sequence and is driven from its three position to its two position. a

When the control shaft of the second printing head is rotated to its two position, no efiective change is produced with respect to the switches 802 and 821 controlled by the shaft. The switch 831 (FIG. 8) closes, but has no control effect, merely restoring the circuit to its original condition. The switch 841 is actuated and changes connections from the timing control switch 242 to the reverse stepping pulse switch 473 which, as noted above, operates in each cycle of the second printing head.

In the next cycle of machine operation, upon closing of the switch 473, the pawl solenoid 896 for the second printing head is again energized. This drives the control shaft of the second printing head from its two position to its one position. No significant change occurs with respect to the switches 802, 831 and 841 controlled by that shaft. The switch 821 closes in preparation for the next printing operation of the machine but makes no significant change in the control sequence for this operation.

On the next cycle of machine operation, the pawl solenoid 896 (FIG. 8) is again energized through the reverse stepping pulse switch 473 (FIG. 9) and drives the main control shaft for the second printing head to its initial or zero position. The switches 821, 831 and 841 remain as they were. The switch 802, however, is returned to its original position, connecting the conductor 510 to the contacts of the relay TDR4. At the same time, this operation of the switch de-energizes the operating coil of the relay TDR4. The contacts 489 and 509, however, remain closed for a predetermined number of machine cycles established by the delay characteristics of the relay.

With the control shaft of the second printing head in its zero position, and with the switch 802 restored to the position shown in the drawings, the blanket cleaner solenoids 341-344 are all energized through an operating circuit that extends through the contacts 509 and the switch 802. This initiates operation of the blanket cleaners in both printing heads, which operation is continued until the contacts of the relay TDR4 subsequently drops out. At the same time, the stop control delay relay TDRl is energized. The operating circuit for this relay, beginning at bus 411, extends through operating coil 428 of the relay (FIG. 9) and through the contacts 489 of the relay TDR4 (FIG. 8) and switches 801, 802 and 434 to the conductor 510.

As may be seen by reference to FIGS. 6 and 6A, the master ejection switch 241 closes shortly after the actuation of the switch 242 that initiates the reverse sequence of operations for the control mechanism for the second printing head. With the switch 241 closed, when the switch 498 in the same circuit is closed (see FIG. 8), as occurs when the main control shaft of the first printing head reaches its zero position, the master ejection solenoids 812 and 813 are energized. As a consequence, the

lithographic masters in each of the two printing heads are automatically ejected, readying the printing machine for the next printing operation.

At the time when the control shaft of the second printing head 61 reaches its zero position, and as the result of energization of the time delay relay TDR4, noted above, the stop delay relay TDRl is energized. This "closes the contacts 426 and 427. The contacts 427 establish a ci-rcuit in parallel with the contacts 425 of the relay CR2 to maintain the holding circuit for the drive motor relay DMR. The closing of the contacts 426 energizes the relay CR2 and opens the contacts 425. Thereafter, the

circuits previously energized through the contacts 425 of Y the relay CR2 are maintained in operation through the contacts 427 of the relay TDRIi. Energization of the relay CR2 also closes the contacts 424 to establish a holding circuit for the relay.

When the desired number of sequences of blanket cleaning operation have been completed, the time delay relay TDR4 drops out. When this occurs, the opening of the contacts 509 de-energizes the blanket cleaner solenoids 341-344. The opening of the contacts 489 opens the operating circuit for the time delay relay TDR1. The contacts 427 and 428 of the relay, however, remain closed for a given time interval to provide for drying of the blanket.

When the time delay relay TDRl has timed out, the contacts 426 and 427 open. Opening of the contacts 427 drops the holding circuit for the relay DMR, which drops out. This results in opening of the contacts 414 and consequently de-energization of the auxiliary bus 429 and all circuits operated thereby. At the same time, all circuits connected to the conductor 422, including particularly the pump motor relay PMR, are de-energized. Accordingly, the entire control circuit is de-energized in preparation for the next printing operation.

The preceding operational description of the automatic sequence control circuit of FIGURES 8 and 9 is based upon automatic control of all operations of the machine subsequent to the application of plate-etch solution to the master cylinders. By actuating certain switches, the printing machine 30 may be conditioned for varying degrees of automatic and manual control.

Perhaps the simplest change which may be made in the operating condition of the circuit of FIGURES 8 and 9 is effected by actuation of the counter on-off switch 452. This particular switch may be moved to its alternate operating position, opening the operating circuit to the count coil 439 in the counter 44. When this is done, the counter is effectively rendered inactive and cannot shut down the printing machine. off position, the operator may stop the printing machine by opening the feed stop switch 463. When this is done, the pump motor relay PMR is deenergized, and the relay TDR6 is also de-energized, with the result that feeding of paper through the printing machine is interrupted. The control relay CR7 also is de-energized, due to the opening of the contacts 478 in the pump motor relay PMR. The drive motor relay DMR, however, is not de-energized by operation of the switch 463. Hence, in order .to interrupt machine operation completely, the operator may actuate either of the stop switches 420 and 421 to open the operating circuit to the relay DMR.

A more substantial change may be effected by actuation of the system-counter switch 446 to its alternate position. In the position illustrated in FIGURE 9, the switch 446 conditions the operating circuit of the machine for control by the counter 44. When actuated with alternate position, however, the switch 446 conditions the machine for automatic control in accordance with the presence or absence of paper in the systems chute of the paper feed mechanism of the machine.

Thus, actuation of the switch 446 to its system feed position connects the contacts 898 of the control relay CR9 into the circuit in place of the counter contacts 441. The contacts 811 of the relay CR9 are substituted in the With the switch 452 in its circuit for the counter contacts 442. Accordingly, shutdown of the printing machine is now made independent of the counter 44. The switch section 447, on the other hand, when actuated to its second or system feed position, connects the vacuum valve solenoid 466 directly to the terminal 468 of the paper, no-paper switch 103. Consequently, the vacuum valve solenoid can be energized only when there is paper in the system chute of the machine. Accordingly the paper-feeding operation is rendered completely independent of control by the counter 44.

Actuation of the switch section 448 of the switch 446 to its alternate or system feed position is effective to establish an alternate energizing circuit for the pawl pulse switch 473. The pawl pulse switch is now dependent upon actuation of the paper, no-paper switch 103, and is energized when the switch .103 reverts to its normal position upon emptying of the systems chute. It is thus seen that the switch 446, when moved to its system feed position, permits substantially automatic operation of the printing machine 30, with interruption of machine operation being controlled by the paper, no-paper switch 103 instead of the counter 44.

The pump motor switch 462 provides for independent control of the paper feeding operation in the printing machine 30. When this switch is actuated to its alternate position, from that shown in FIGURE 8, the pump motor relay PMR is energized directly through an operating circuit including the switch. 462, the normally closed contacts 425 of the relay CR2 (FIGURE 9), and the main bus 410. The feeder and blower solenoids 133 and 133A are energized through the same circuit. The vacuum valve solenoid 466 is energized through the normally closed contacts of the relay DMR. Thus, the pump motor switch 462 efiectively provides for feeding of paper independently of the automatic sequence control previously described.

The switch 433, when actuated from the automatic position illustrated in FIGURES 8 and 9 to the alternate manual position, effects a substantially complete change in the mode of operaton of the printing machine 30. When the switch 433 is actuated to its manual position, automatic operation of the printing machine 30 is no longer possible. Instead, it is now necessary for the machine operator to control all of the machine operations, in essentially the same manner as with a conventional manual-operated ofiset duplicating machine.

From the foregoing it can be understood that this invention provides a two-head, tandem printing machine especially adapted to systems applications, producing high quality copies under short run conditions while requiring minimum operator attention. One feature in particular that should be emphasized is that by employing a timing control mechanism of the type indicated by reference character 200, the machine is made to have an important degree of flexibility. The description has proceeded upon the basis that the settings of the cams which control switches 241, 242 and 243 are such as to provide for a three cycle delay between the first head and the second, at least as to certain of their operations. This delay, however, is normally required only when both sides of the sheet are being printed and time is required to invert the sheet between heads. If, for example, it is desired to bypass the sheet inverter. and use the machine to print two colors on one surface only of the sheet, it might be preferable to have only a two-cycle delay between the critical operations of the two heads. Such a change, as well as a change to a four cycle delay can be readily eifected by merely resetting the adjustable cams on the shaft 212, so that the machine is highly adaptable.

While preferred embodiments of the invention have been described and illustrated, it is to be understood that these are capable of variation and modification. Accordingly, the aim in the appended claims is to cover all such variations and modifications as may fall within the true spirit of the invention.

What is claimed is:

1. In an offset printing machine of the kind comprising first and second printing heads connected in tandem and driven in unison to perform two sequential printing operations on each of a plurality of print-receiving sheets, each printing head including a master cylinder, a blanket cylinder, a main control member movable between an initial position, at least one intermediate operating position, and a final operating position, repellent applicator means for applying an ink repellent solution to said master cylinder, inking means for, applying ink to a planographic master mounted on said master cylinder, blanket imaging means for moving one of said master and blanket cylinders from an initial position displaced from the other cylinder into a blanket-imaging contact position therewith, means operatively connecting said repellent applicator means, said inking means, and said blanket imaging means to said main control member for actuation in predetermined sequence in response to movement of said main control member, and an electrically actuated control mechanism for advancing said main control member between said positions, sequence control means comprising:

first circuit means for actuating the control mechanism of said first printing head to advance the first main control member step-by-step from its initial operating position to its final operating position;

second circuit means connecting the control mechanism of said second printing head to said first circuit means for actuation to advance the second main control member to intermediate position in unison with the first main control member;

and prog'rarncontrol means, connected in said second circuit means, for precluding actuation of the second control mechanism from said first circuit means when said main control members are in their intermediate positions and for energizing said second circuit means independently of said first circuit means to advance said second main control member to final position a predetermined number of machine cycles atter the first main control member is advanced to its final operating position.

2. In an offset printing machine of the kind comprising first and second printing heads connected in tandem and having a common machine drive for driving said printing heads in unison to perform two sequential printing operations on each of a plurality of print-receiving sheets, each printing head including a master cylinder, a blanket cylinder, a main control member movable between an initial position, at least one intermediate operating position, and a final operating position, repellent applicator means for applying an ink repellent solution to said master cylinder, inking means for applying ink to a planognaphic master mounted on said master cylinder, blanket imaging means for moving one of said master and blanket cylinders from an initial position displaced from the other cylinder into a blanket-imaging contact position therewith, means operatively connecting said repellent applicator means, said inking means, and said blanket imaging means to said main control member for actuation in predetermined sequence in response to movement of said main control member, and an electrically actuated control mechanism for advancing said main control member between said positions, sequence control means comprising:

first circuit means for actuating the control mechanism of said first printing head to advance the first main control member step-by-step from its initial operating position to its final operating position;

second circuit means connecting the control mechanism of said second printing head to said first circuit means for actuation to advance the second main control member to intermediate position in unison with the first main control member;

and program control means, connected in said second circuit means, for precluding actuation of the second control mechanism from said first circuit means when said main control members are in their intermediate positions and for energizing said second circuit means independently of said first circuit means to advance said second main control member to final position a predetermined number of machine cycles after the first main control member is advanced to its final operating position;

said program control means comprising a shaft, drive means including a normally disengaged clutch connecting said shaft to said machine drive to rotate said shaft through a full revolution in response to rotation of said cylinders through a given number of revolutions, at least one control switch actuated by rotational movement of said shaft through a predetermined angular displacement, and means for engaging said clutch upon movement of said first main control member to its final operating position.

3. In an offset printing machine of the kind comprising first and second printing heads connected in tandem and driven in unison to perform two sequential printing operations on each of a plurality of print-receiving sheets, each printing head including a master cylinder, a blanket cylinder, a main control member movable from an initial position to at least one intermediate operating position and to a final operating position and back to said initial position, repellent applicator means for applying an ink repellent solution to said master cylinder, inking means for applying ink to a planographic master mounted on said master cylinder, blanket imaging means for moving one of said master and blanket cylinders from an initial position displaced from the other cylinder into a blanketimaging contact position therewith, means operatively connecting said repellent applicator means, said inking means, said blanket imaging means to said main control member for actuation in predetermined sequence in response to movement of said main control member, and an electrically actuated control mechanism for advancing said main control member between said positions, sequence control means comprising:

first circuit means for actuating the control mechanism of said first printing head to advance the first main control member step-by-step from its initial operating position to its intermediate position, to its final operating position, and subsequently back to its initial position;

second circuit means connecting the control mechanism of said second printing head to said first circuit means for actuation to advance the second main control member to its intermediate position in unison with the first main control member;

and program control means, connected in said second circuit means, for controlling actuation of the second control mechanism,

said program control means including a control device connected in series in the circuit from said first circuit means to said second circuit means and responsive to movement of one of said main control members to open that circuit when said one main control member is in its intermediate position,

said program control means further including means for energizing said second circuit means independently of said first circuit means to advance said second main control member to its final position and to return said second main control member to its intermediate position a predetermined number of machine cycles after the corresponding movements of the first main control member.

4. In an offset printing machine of the kind comprising first and second printing heads connected in tandem and having a common machine drive for driving said printing heads in unison to perform two sequential printing operations on each of a plurality of print-receiving sheets, each printing head including a master cylinder, a blanket cylinder, a main control member movable from an initial position to at least one intermediate operating position and to a final operating position and back to said initial position, repellent applicator means for applying an ink repellent solution to said master cylinder, inking means for applying ink to a planographic master mounted on said master cylinder, blanket imaging means for moving one of said master and blanket cylinders from an initial position displaced from the other cylinder into a blanketimaging contact position therewith, means operatively connecting said repellent applicator means, said inking means, and said blanket imaging means to said main control member for actuation in predetermined sequence in repsonse to movement of said main control member, and an electrically actuated control mechanism for advancing said main. control member between said positions, sequence control means comprising:

first circuit means for actuating the control mechanism of said first printing head to advance the first main control member step-by-step from its initial operating position to its intermediate position, to its final operating position, and subsequently back to its initial position;

second circuit means connecting the control mechanism of said second printing head to said first circuit means for actuation to advance the second main control member to its intermediate position in unison with the first main control member;

and program control means, connected in said second circuit means, for controlling actuation of the second control mechanism,

said program control means including a control device connected in series in the circuit from said first circuit means to said second circuit means and responsive to movement of one of said main control members to open that circuit when said one main control member is in its intermediate position,

said program control means further including timing means for energizing said second circuit means independently of said first circuit means to advance said second main control member to its final position and to return said second main control member to its intermediate position a predetermined number of machine cycles after the corresponding movements of the first main control member,

said timing means comprising a rotatable shaft, drive means including a normally disengaged clutch conmeeting said shaft to the said machine drive to rotate said shaft in predetermined ratio to rotation of said cylinders, a first control switch actuated by rotational movement of said shaft and connected to said second printing head to advance the second main control member to its final position, a second control switch actuated by rotational movement of said shaft and connected to said second circuit means for actuating said control mechanism of said second printing head to move said second main control member from its final position to its intermediate position, and means for engaging said clutch upon movement of said first main control member between its intermediate position and final operating positions.

5. In an offset printing machine of the kind comprising first and second printing heads connected in tandem and driven in unison to perform two sequential printing operations on each of a plurality of print-receiving sheets, each printing head including a master cylinder, a blanket cylinder, a main control member movable between an initial position, at least one intermediate operating position, and a final operating position, and back to said initial position, repellent applicator means for applying an ink repellent solution to said master cylinder, inking means for applying ink to a planographic master mounted on said master cylinder, blanket imaging means for moving one of said master and blanket cylinders from an initial position displaced from the other cylinder into a blanket-imaging contact position therewith, blanket cleaning means, means operatively connecting said repellent applicator 28 means, said inking means, and said blanket imaging means to said main control member for actuation in predetermined sequence in response to movement of said main control member, and an electrically actuated control mechanism for advancing said main control member between said positions, sequence control means comprising:

first circuit means for actuating the control mechanism of said first printing head to advance the first main control member step-by-step from its initial operating position to its final operating position and back to its initial position; second circuit means connecting the control mechanism of said second printing head to said first circuit means for actuation to advance the second main control member between its initial and intermediate positions in unison with the first main control member;

program control means, connected in said second circuit means, for precluding actuation of the second control mechanism from said first circuit means when said main control members are in their intermediate positions and for energizing said second circuit means independently of said first circuit means to move said second man control member between its intermediate and final positions a predetermined number of machine cycles after the corresponding movements of said first main control member;

and means for actuating said blanket cleaners after both of said main control members are returned to their initial positions. 6. In an oiTset printing machine of the kind comprising first and second printing heads connected in tandem and driven in unison to perform two sequential printing operations on each of a plurality of print-receiving sheets, each printing head including a master cylinder, a blanket cylinder, a main control member movable between an initial position, at least one intermediate operating position, and a final operating position, and back to said initial position, repellent applicator means for applying an ink repellent solution to said master cylinder, inking means for applying ink to a planographic master removably mounted on said master cylinder, blanket imaging means for moving one of said master and blanket cylinders from an initial position displaced from the other cylinder into a blanket-imaging contact position therewith, master ejection means for ejecting the master from said master cylinder, means operatively connecting said repellent applicator means, said inking means, and said blanket imaging means to said main control member for actuation in predetermined sequence in response to movement of said main control member, and an electrically actuated control mechanism for advancing said main control member between said positions, sequence control means comprising:

first circuit means for actuating the control mechanism of said first printing head to advance the first main control member step-by-step from its initial operating position to its final operating position and back to its initial position; second circuit means connecting the control mechanism of aid second printing head to said first circuit means for actuation to advance the second main control member between its initial and intermediate positions in unison with the first main control member;

program control means, connected in said second circuit means, for precluding actuation of the second control mechanism from said first circuit means when said main control member are in their intermediate positions and for engaging said second circuit means independently of said first circuit means to move said second main control member between its intermediate and final positions a predetermined number of machine cycles after the corresponding movements of said first main control member;

and means for actuating both of said master ejector means after said main control members are returned to their initial positions.

7. In an offset printing machine of the kind comprising first and second printing heads connected in tandem and having a common machine drive for driving said printing heads in unison to perform two sequential printing operations on each of a plurality of print-receiving sheets, each printing head including a master cylinder, a blanket cylinder, a main control member movable from an initial position to at least one intermediate operating position and back to said initial position, repellent applicator means for applying an ink repellent solution to said master cylinder, inking means for applying ink to a planographic master mounted on said master cylinder, blanket imaging means for moving one of said master and blanket cylinders from an initial position displaced from the other cylinder into a blanket-imaging contact position therewith, electrically actuated blanket cleaning means, electrically actuated master ejecting means for ejecting the master from said master cylinder, means operatively connecting said repellent applicator means, said inking means, said blanket imaging means to said main control member for actuation in predetermined sequence in response to movement of said main control member, and an electrically actuated control mechanism for advancing said main control member between said positions, sequence control means comprising:

first circuit means for actuating the control mechanism of said first printing head to advance the first main control member step-by-step from its initial operating position to its intermediate position, to its final operating position, and subsequently back to its initial position;

second circuit means connecting the control mechanism of said second printing head to said first circuit means for actuation to advance the second main control member to its intermediate position in unison with the first main control member;

program control means, connected in said second circuit means, for controlling actuation of the second control mechanism, said program control means including a control device connected in series in the circuit from said first circuit means to said second circuit means and responsive to movement of one of said main control members to open that circuit when said one main control member is in its intermediate position,

said program control means further including timing means for energizing said second circuit means independently of said first circuit means to advance said second main control member to its final position and to return said second main control member to its intermediate position a predetermined number of machine cycles after the corresponding movements of the first main control member,

said timing means comprising a rotatable shaft, drive means including a normally disengaged clutch connecting said shaft to the said machine drive to rotate said shaft in predetermined ratio to rotation of said cylinders, a first control switch actuated by rotational movement of said shaft and connected to said second circuit means for actuating the control mechanism of said second printing head to advance the second main control member to its final position, a second control switch actuated by rotational movement of said shaft and connected to said second circuit means for actuating said control mechanism of said second printing head to move said second main control member from its final position to its intermediate posit-ion, a third control switch, and means for engaging said clutch upon movement of said first main control member between its intermediate position and its final operating position,

and means, including said third control switch, for actuating said master ejector means and said blanket cleaner means for both printing heads after said main control members return to their initial positions. 8. In an offset printing machine comprising tandem connected first and second olfset printing heads, and wherein each printing head includes an electrically actuated control mechanism that has a control member movable between an initial position, at least one intermediate position, and a final printing position to thereby control means for applying an ink repellent solution to a master removably mounted in the head, means for inking the master, and means for imaging a blanket from the master, sequence control means comprising:

first and second circuit means for actuating the control mechanisms of said first and second printing heads, respectively, to advance the control members thereof step-by-step from their respective initial positions to their final printing positions; means interconnecting said first and second circuit means whenever said control members are in their respective initial positions to assure advancement of said control members to their intermediate positions in unison with each other; and program control means, connected in said second circuit means, for energizing said second circuit means independently of said first circuit means to advance said second control member to final printing position a predetermined number of machine cycles after the first control member is advanced to its final printing position. 9. In an offset printing machine comprising tandem connected first and second offset printing heads and wherein each printing head includes an electrically actuated control mechanism that has a control member movable between an initial position, at least one intermediate position, and a final printing position to thereby control means for applying an ink repellent solution to a master removably mounted in the head, means for inking the master, means for imaging a blanket from the master, and means for cleaning the blanket, sequence control means comprising:

first and second circuit means for actuating the control mechanisms of said first and second printing heads, respectively, to advance the control members thereof step-by-step from their respective initial positions to their final printing positions and back again;

means interconnecting said first and second circuit means whenever said control members are in their respective initial positions to assure advancement of said control members from their initial positions to their intermediate positions and retraction of said control members back from their intermediate positions to their initial positions in unison with each other;

and program control means, connected in said second circuit means, for energizing said second circuit means independently of said circuit means to advance said second control member from intermediate position to final printing position and to retract said second control member from final printing position to intermediate position a predetermined number of machine cycles after the corresponding movements of the first control member.

10. In an otfset printing machine comprising tandem connected first and second offset printing heads, and in which each printing head includes an electrically actuated control mechanism that has a control member movable between an initial position, at least one intermediate position, and a final printing position to thereby control means for applying an ink repellent solution to a master removably mounted in the head, means for inking the master, means for imaging a blanket from the master, 

1. IN AN OFFSET PRINTING MACHINE OF THE KIND COMPRISING FIRST AND SECOND PRINTING HEADS CONNECTED IN TANDEM AND DRIVEN IN UNISON TO PERFORM TWO SEQUENTIAL PRINTING OPERATIONS ON EACH OF A PLURALITY OF PRINT-RECEIVING SHEETS, EACH PRINTING HEAD INCLUDING A MASTER CYLINDER, A BLANKET CYLINDER, A MAIN CONTROL MEMBER MOVABLE BETWEEN AN INITIAL POSITION, AT LEAST ONE INTERMEDIATE OPERATING POSITION, AND A FINAL OPERATING POSITION, REPELLANT APPLICATOR MEANS FOR APPLYING AN INK REPELLENT SOLUTION TO SAID MASTER CYLINDER, INKING MEANS FOR APPLYING INK TO A PLANOGRAPHIC MASTER MOUNTED ON SAID MASTER CYLINDER, BLANKET IMAGING MEANS FOR MOVING ONE OF SAID MASTER AND BLANKET CYLINDERS FROM AN INITIAL POSITION DISPLACED FROM THE OTHER CYLINDER INTO A BLANKET-IMAGING CONTACT POSITION THEREWITH, MEANS OPERATIVELY CONNECTING SAID REPELLANT APPLICATOR MEANS, SAID INKING MEANS, AND SAID BLANKET IMAGING MEANS TO SAID MAIN CONTROL MEMBER FOR ACTUATION IN PREDETERMINED SQUENCE IN RESPONSE TO MOVEMENT OF SAID MAIN CONTROL MEMBER, AND AN ELECTRICALLY ACTUATED CONTROL MECHANISM FOR ADVANCING SAID MAIN CONTROL MEMBER BETWEEN SAID POSITIONS, SEQUENCE CONTROL MEANS COMPRISING: FIRST CIRCUIT MEANS FOR ACTUATING THE CONTROL MECHANISM OF SAID FIRST PRINTING HEAD TO ADVANCE THE FIRST MAIN CONTROL MEMBER STEP-BY-STEP FROM ITS INITIAL OPERATING POSITION TO ITS FINAL OPERATING POSITION; SECOND CIRCUIT MEANS CONNECTING THE CONTROL MECHANISM OF SAID SECOND PRINTING HEAD TO SAID FIRST CIRCUIT MEANS FOR ACTUATION TO ADVANCE THE SECOND MAIN CONTROL MEMBER TO INTERMEDIATE POSITION IN UNISON WITH THE FIRST MAIN CONTROL MEMBER; AND PROGRAM CONTROL MEANS, CONNECTED IN SAID SECOND CIRCUIT MEANS, FOR PRECLUDING ACTUATION OF THE SECOND CONTROL MECHANISM FROM SAID FIRST CIRCUIT MEANS WHEN SAID MAIN CONTROL MEMBERS ARE IN THEIR INTERMEDIATE POSITIONS AND FOR ENERGIZING SAID SECOND CIRCUIT MEANS INDEPENDENTLY OF SAID FIRST CIRCUIT MEANS TO ADVANCE SAID SECOND MAIN CONTROL MEMBER TO FINAL POSITION A PREDETERMINED NUMBER OF MACHINE CYCLES AFTER THE FIRST MAIN CONTROL MEMBER IS ADVANCED TO ITS FINAL OPERATING POSITION. 